Ultraviolet luminescence spectra of boron nitride single crystals grown under high pressure and high temperature
Ultraviolet luminescence spectra of boron nitride single crystals grown under high pressure and high temperature
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DOI：
10.1002/pssa.200405188
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发表时间：
2004-09
期刊：
影响因子：
--
通讯作者：
Kenji Watanabe;T. Taniguchi;H. Kanda
中科院分区：
文献类型：
--
作者：
Kenji Watanabe;T. Taniguchi;H. Kanda
采用温度梯度法在高温高压条件下生长的氮化硼（BN）单晶，在200 nm附近的紫外区显示出与激子相关的阴极发光峰。从立方相BN单晶的一系列峰被指定为声子辅助的自由激子发光带的间接激子的间隙能量估计为6.17 eV。激子的结合能估计为80毫电子伏的激子发光强度的温度依赖性的基础上。在215 nm处观察到六方相BN单晶的主发光峰，其发光强度是IIa型金刚石的间接激子发光强度的1000倍。这种强烈的发光表明六方BN是直接带隙材料。
Boron nitride (BN) single crystals grown by employing a temperature gradient method under high-pressure and high-temperature conditions using a carefully purified Ba-B-N solvent system showed exciton-related cathodoluminescence peaks in the ultraviolet region around 200 nm. A series of peaks from the cubic phase of BN single crystal was assigned as the phonon-assisted free-exciton luminescence bands from which the indirect exciton gap energy was estimated to be 6.17 eV. The exciton binding energy was estimated to be 80 meV based on the temperature dependence of the exciton luminescence intensity. A dominant luminescence peak from hexagonal-phase BN single crystal was observed at 215 nm, which is 1000 times larger than the indirect exciton luminescence of type IIa diamond. This intense luminescence suggests that hexagonal BN is a direct band gap material.